[U-Boot] Problem with initialize in mmc_initialize in mmc.c

[Jaehoon Chung]

Hi Faiz,

On 11/02/2017 11:23 PM, Faiz Abbas wrote:
> 
> 
> On Monday 30 October 2017 07:37 PM, Faiz Abbas wrote:
>> Hi,
>>
>> The variable *initialized* in mmc_initialize() is declared as static and
>> initialised to 0 in the following commit. This makes the compiler put it
>> in the .bss section of the image.
>>
>> commit 1b26bab12e85e8b0d382d6775e40d14445249574
>> Author: Daniel Kochmański <dkochmanski at turtle-solutions.eu>
>> Date:   Fri May 29 16:55:43 2015 +0200
>>
>>     mmc: Protect `mmc_initialize` from initialising mmc multiple times
>>
>>     `mmc_initialize` might be called multiple times leading to the
>> mmc-controllers being initialised twice, and initialising the
>> `mmc_devices` list head twice which may lead to memory leaks.
>>
>>     Signed-off-by: Daniel Kochmański <dkochmanski at turtle-solutions.eu>
>>     CC: Roy Spliet <r.spliet at ultimaker.com>
>>     Cc: Ian Campbell <ijc at hellion.org.uk>
>>     CC: Pantelis Antoniou <panto at antoniou-consulting.com>
>>     Acked-by: Hans de Goede <hdegoede at redhat.com>
>>     Signed-off-by: Hans de Goede <hdegoede at redhat.com>
>>
>> diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
>> index da47037..f12546a 100644
>> --- a/drivers/mmc/mmc.c
>> +++ b/drivers/mmc/mmc.c
>> @@ -1762,6 +1762,11 @@ static void do_preinit(void)
>>
>>  int mmc_initialize(bd_t *bis)
>>  {
>> +       static int initialized = 0;
>> +       if (initialized)        /* Avoid initializing mmc multiple times */
>> +               return 0;
>> +       initialized = 1;
>> +
>>         INIT_LIST_HEAD (&mmc_devices);
>>         cur_dev_num = 0;
>>
>>
>> .bss should not be accessed in u-boot before relocation because it
>> overlaps with fdt and writing to variables in .bss can corrupt the fdt.
>> MMC can be probed before relocation if it contains the u-boot
>> environment. Therefore, I tried to move this variable to the .data
>> section by

Will check with T32..but i didn't have seen about similar case..
You means it should be the multiple initializing?

Best Regards,
Jaehoon Chung

>>
>> static int initialized __attribute__((section(".data")));
>>
>> When *initialized* was a part of .bss it was getting re-initilized to 0
>> as a part of relocation. Therefore, mmc was getting probed again
>> successfully after relocation with new addresses for mmc devices.
>>
>> Now when *initialized* is not a part of .bss, it holds its value across
>> relocation and a second call to mmc_initialize() returns without doing
>> anything. However, the *mmc_devices* list containing pointers to the
>> older locations of mmc devices is not refreshed and thus mmc devices
>> fail to enumerate.
>>
>> So *initialized* is a problem whether it is in .data or .bss.
>> I am not sure how to fix this. Any help is appreciated.
> 
> I have been told that all pointers are supposed to be updated during
> relocation. Can anyone point to relevant code or example of the same?
> 
> Thanks,
> Faiz
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